There are many situations in the business world where it is desirable to record both a beginning time and a finishing time for an event for eventual conversion to a figure indicative of elapsed time. Such a situation exists in the case of the timing of long distance telephone calls. For this purpose, the telephone operator is provided with a time recorder having a slot into which she inserts a card for each long distance telephone call made. She inserts the card and presses an actuator so that the starting time is printed on the card. After the telephone call is over, she again inserts the same card and presses the same handle to record the time again. A time interval is shown, this often being accomplished on a dial which is printed on the card. Since the operator has limited space on her console, it is desirable that this time recorder be quite thin and that it be adapted for flush mounting. In addition, modern business methods have led to optical scanning of such cards for the purpose of computing bills. In the past, time recorders have suffered from a number of disabilities that prevent this type of operation from being entirely successful. For one thing, the limited space available in thin time recorders has resulted in a printed character that is not clear and distinct. Furthermore, under certain conditions, the time printing wheels, particularly those which are faster moving (such as the 1/10th of a minute wheel) often rotate to positions between characters, so that no character is printed, and the optical scanner is unable to find a character to record. Attempts to move such a wheel incrementally to assure that one character or another is properly centered at the moment of printing has not only resulted in gain and loss of time in the total recording of the time stamp, but also has resulted in worn pawls and ratchets for accomplishing this purpose. These and other difficulties experienced with the prior art devices have been obviated in a novel manner by the present invention.
It is, therefore, an outstanding object of the invention to provide a time recorder which, although small in size, is capable of giving a clear printed character.
Another object of this invention is the provision of a time recorder in which the fastest moving time wheel is driven continuously to avoid the use of pawl and ratchets, but which, nevertheless, centers each character adequately.
A further object of the present invention is the provision of a time recorder capable of giving a printed image particularly adaptable to optical scanning.
It is another object of the instant invention to provide a time recorder in which one of the time stamp wheels is continuously driven, in which, at the time of printing, the nearest character is brought into a predetermined line, and in which, after printing, is returned to the position at which it would have resided if printing had not taken place.
A still further object of the invention is the provision of a time recorder having time print wheels operated by pawls, in which the wheels are securely locked against movement except at the moment when a pawl engages a wheel, and in which the unlocking mechanism is not capable of accidentally moving into a condition where all of the wheels remain unlocked.
It is a further object of the invention to provide a time stamp of the pawl-and-ratchet type which is provided with a locking means which is very unlikely to accidentally catch in unlocked condition.
It is a still further object of the invention to provide a time recorder whose elements are readily accessible for inspection and repair.
Another object of the invention is the provision of a time recorder of simple and rugged construction which is capable of a long life of useful service with a minimum of maintenance.
With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.